1. Field of the Invention
This invention relates to a canister apparatus for an internal combustion engine used for preventing harmful gas from diffusing to atmosphere by absorbing fuel vapor occurring upon fuel evaporation, and more particularly to a canister apparatus for preventing water from flowing into activated carbon so that the absorbing efficiency of the activated carbon can be further improved.
2. Description of the Prior Art
As shown in FIG. 1, a canister apparatus for preventing harmful gas from diffusing to atmosphere by absorbing fuel vapor occurring upon fuel evaporation includes a main body 1 having a lot of activated carbons 2 therein, a first guide pipe 3 for guiding fuel vapor to the main body 1, a second guide pipe 4 connected to the main body 1 for discharging fuel-air mixture from the main body 1 to engine, and a third guide pipe 7 connected to the main body 1 for introducing air into the main body 1.
An air tank 5 having a filter 6 therein for filtering harmful materials such as dust included in the air is installed at a lateral side of the body 1 and a suction port 8 is formed at a bottom surface of the air tank 5.
In such a conventional canister apparatus, fuel vapor vaporized at a fuel tank is guided by the first guide member 3 to flow into the main body 1, and the fuel vapor infused into the main body 1 becomes absorbed by activated carbons 2 filled in the body 1.
Therefore, diffusion of harmful gas to the atmosphere is restrained to prevent air pollution because the fuel vapor is absorbed by the activated carbons 2.
Meanwhile, when an engine is operated, air in the atmosphere is sucked through the suction port 8 formed at the air tank 5. The sucked air is provided into the main body 1 by being guided by a third guiding member 7 after harmful materials such as dust included in the sucked air are filtered by the filter 6 installed at the air tank 5.
Then, the air provided to the main body 1 is mixed with fuel vapor absorbed in the activated carbon 2 by negative pressure generated in an intake manifold to thereby be inverted into an air-fuel mixture. The air-fuel mixture is provided to the engine to be burned and guided by a third guide member 7.
However, there is a problem in the conventional canister apparatus, in that when it rains or a vehicle passes over a puddle, water may flow into the air tank 5 since the air tank 5 is installed at a side of the canister exposed outside of the bottom of the vehicle. Such water soaked into the air tank 5 flows into the main body 1 through the third guide member 7.
In other words, there is a problem in the conventional canister apparatus in that if water flows into the main body 1, fuel vapor absorbing efficiency of the activated carbons decreases, so that some harmful fuel vapor not having been absorbed by the activated carbons, is diffused to the atmosphere and contaminates the atmosphere.
Accordingly, it is an object of the present invention to provide a canister apparatus for restraining diffusion of harmful gas to the atmosphere in order to thereby prevent air pollution by avoiding water from flowing into the main body for preservation of the fuel vapor absorbing efficiency of the activated carbons.